The use of fibers as a binder for agglomerates can be practiced for a plurality of particle types, especially of inorganic materials, particularly ores and ore concentrates, such as iron ores, e.g. hematite, magnetite or other iron oxide materials comprising one or more of the oxides FeO, Fe.sub.3 O.sub.4 and Fe.sub.2 O.sub.3 as well as other iron oxide materials, such as hydrated oxides, etc. See, for example, Canadian Patent No. 1,002,761, Jan. 4, 1977.
Other suitable agglomeratable materials are ores of nickel, cobalt, copper, zinc, lead, tungsten, etc. as well as other materials in agglomerated form, e.g. catalyst materials or carriers for catalyst materials, such as alumina.
Agglomeration methods of various types may be used, preferably rolling of particled materials into pellets in devices comprising drums, cones or discs.
Agglomeration by rolling to pellets is usually performed with the addition of a liquid, preferably water or an aqueous solution of organic or inorganic materials. It is also possible to include other binders which are commonly used for agglomeration, such as organic binders of various types especially polymeric materials, such as cellulose and cellulose derivatives, starch materials, curable resins, etc., and inorganic additives, such as bentonite or other clays, lime, cement, such as Portland cement, slag cement, alumina cement etc. The use of inorganic materials, such as bentonite, is widely practiced in producing pellets of iron ore, but: bentonite is known to add silica and alumina and thereby contaminates the concentrate. To compensate, the ore has to be upgraded more than is usually necessary, based on the specification of the final pellet composition, thus representing an additional cost and a source of variability in pellet chemistry. Organic binders avoid this contamination, but are often too expensive or commercially unavailable. Inorganic fibrous materials such as glasswool fibers, rockwool fibers slagwool and the like have been proposed, see, for example, World Patent No 80/02566, Nov. 27, 1980, but, in spite of their low cost, have been found difficult to handle and to generally cause environmental problems. Organic polymeric materials, both natural and synthetic, such as cellulose pulp, wool fibers, rayon fibers, nylon fibers, and the like, have been used, see, for example, the above-mentioned Canadian Patent No. 1,002,761, but the quantity of the fibers exemplified, e.g., 1% by weight (20 lbs/ton) based on the ore makes, them too expensive to be a commercially attractive replacement for the inorganics. Another factor to be considered is the desirability of using a binder which does not chemically affect the reduction process normally used in converting ores to metal values. Bentonite and other clays render the pellets acidic and interfere with direct reduction. Organic binders, on the other hand, do not lead to such interference. In the present state of the art, it is therefore desirable to provide organic binders, but only those effective at low concentrations, in order to produce pellets or other agglomerates which overcome the disadvantages of the prior art. It has been found that such agglomerates are produced if specific fibrous polymers comprising units derived from acrylonitrile are used as binders.